1. Field of the Invention
The present invention relates to a packet transmission system, a packet transmission method, a packet update method, a host apparatus and a computer program product thereof for the packet transmission system. In particular, the present invention relates to a packet transmission system that increases the positioning speed and accuracy by using two-way transmission of packets, and a packet transmission method, a packet update method, a host apparatus and a computer program product thereof for the packet transmission system.
2. Descriptions of the Related Art
Over recent years, with the widespread use of mobile communications, mobile communication apparatuses are becoming more diversified and prevalent. However, current mobile communication apparatuses commercially available, for example, those compatible with Global System for Mobile Communications (GSM), Wideband Code Division Multiple Access (WCDMA), General Packet Radio Service (GPRS), Personal Handy Phone System (PHS), Wireless Fidelity (WiFi) System or Worldwide Interoperability for Microwave Access (WiMAX), all utilize base stations to provide voice, image and data communications and mobile apparatus positioning service.
However, the aforesaid mobile communication systems can provide the positioning service with satisfactory accuracy only when the mobile apparatus is not moving at a high speed or not moving continuously. For instance, only when the user uses the positioning function of a Personal Digital Assistant (PDA) at a fixed location or in a vehicle moving at a low speed, can the aforesaid mobile communication systems provide positioning functions adequate to allow the user to know his own position exactly while still allowing for various communications such as voice, image and data communications. Moreover, the positioning functions of the aforesaid mobile communication systems are mostly limited to coverage areas due to the electromagnetic waves transmitted by the base stations thereof.
However, if a mobile apparatus provides positioning functions with high accuracy only when it is located at a fixed location or moving at a low speed, it will fail to meet requirements of the modern society in most cases. For instance, for a business person in a bus running on an expressway or a train running at a high speed, the positioning function of his mobile apparatus will experience a degradation in positioning accuracy or even failure of the positioning function due to loss of positioning packets transmitted between the mobile apparatus and host apparatus (e.g., a server or switch).
Furthermore, in addition to the problem with positioning accuracy, the aforesaid mobile communication systems all have to establish data transmission channels with the base stations or the host apparatuses continuously to position the mobile apparatus by performing the positioning function at any time. Because of this, the mobile apparatus has to transmit and receive various positioning information on a continuous basis, leading to considerable power consumption.
In view of this, it is important to improve the accuracy of positioning a mobile apparatus while transmitting information and reduce power consumption.